The present invention relates to a curable silicone composition for a liquid gasket and more particularly a composition for a liquid gasket which is used as FIPG (Formed In-Place Gasket) in an assembling process of automobile parts, electric and electronic parts, etc. and which increases in viscosity upon radiation of ultraviolet ray thereto and is superior in both working efficiency and initial pressure resistance at the time of mounting (the pressure resistance is checked in the assembling process before complete curing of the liquid gasket).
In connection with using as FIPG, there is known a method wherein, in a moisture-curable RTV silicone comprising a one-pack type condensation-curable composition which contains an organosiloxane as a main component, the molecular weight of a polysiloxane is made larger or the amount of an inorganic filler to be incorporated in the composition is increased to attain an increase in viscosity for obtaining a high initial pressure resistance at the time of mounting. It is also known that, in an anaerobic adhesive, partial curing is allowed to take place by the radiation of ultraviolet ray, followed by anaerobic curing (Japanese Patent Laid Open No. 104976/1983). It is also known that an ultraviolet-curing resin is allowed to cure completely at a flange interface and thereafter another flange is mounted (Japanese Patent Laid Open No. 77597/1987).
However, a sealing material which has been made high in viscosity for attaining a high initial pressure resistance causes a discharge pump or a dispenser of a coating machine to be overloaded, thus making it difficult to form a bead precisely and efficiently. The anaerobic adhesive disclosed in Japanese Patent Laid Open No. 104976/1983 involves problems; for example, it does not cure in thick film, a protruded portion from a flange portion does not cure, and it is difficult to cure in flanges (plastic parts) other than metal flanges. Further, the gasket layer pre-formed at a flange interface, which is disclosed in Japanese Patent Laid Open No. 77597/1987, cannot afford a high pressure resistance unless clamping is made strongly because it is not bonded to another flange, and a too strong clamping may cause stress-cracking of the gasket layer.
It is the object of the present invention to overcome the above-mentioned problems of the prior art.